In cellular devices and other wireless devices, the transmitter typically includes a power amplifier that drives an antenna for wireless signal transmission, where the power amplifier is further driven by a pre-amplifier. Forward power (e.g., power being sent to the antenna) is typically measured for power control in a wireless transmitter. The power level is monitored to get an estimate of the signal power that is being radiated by the antenna.
However, the accuracy and usefulness of these forward power measurements can be affected by the input impedance of the antenna, which can vary based on objects that are placed in the vicinity of the antenna during operation. When the antenna impedance varies, the impedance match with the output of the power amplifier is affected, and power is reflected back from the antenna to the power amplifier. Accordingly, as the antenna impedance changes, the actual power radiated by the antenna is not the same as the detected forward power because some portion of the power is reflected back from the antenna due to the impedance mismatch between the two devices.
What is needed therefore are systems and methods for adjusting the power sent to an antenna as antenna impedance changes.
Features and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.